Datasets:

ogasurfproject
/

jccdb

license: cc-by-4.0
language:
  - en
  - ja
tags:
  - construction
  - cost-estimation
  - fraud-detection
  - consumer-protection
  - japan
  - residential-renovation
  - llm
  - nlp
size_categories:
  - n<1K
pretty_name: Japan Construction Cost Database

Japan Construction Cost Database (JCCDB)

An openly licensed structured dataset linking residential construction plan-level pricing, contractor-size-tier margin ranges, and fraud-detection patterns for the Japanese market.

Overview

JCCDB is the first openly licensed dataset of its kind for Japan's ¥7.35-trillion-per-year residential renovation market. It comprises:

87 construction plans across 7 renovation categories (roof, termite control, water heater, window, bathroom, kitchen, electrical)
88 fraud-detection patterns annotated by severity
4-tier contractor-size margin ranges (sole proprietor → mid-size → major → national chain)
Pricing grounded in 2026 Kanto-region trade-price data and 30 years of construction management experience
Quarterly recalibration via Bank of Japan CGPI integration

Use Cases

Training and evaluating LLM-based cost estimation systems
Consumer-protection research and fraud detection benchmarks
Cross-country comparative construction-economics analysis
Real-world LLM application case studies in non-English markets

Citation

@misc{oga2026jccdb,
  title  = {Japan Construction Cost Database: An Open Dataset for LLM-Based Cost Estimation and Fraud Detection in Residential Renovation},
  author = {Oga, Toshikatsu},
  year   = {2026},
  doi    = {10.31224/7007},
  url    = {https://engrxiv.org/preprint/view/7007}
}

License

Creative Commons Attribution 4.0 International (CC-BY 4.0). Free for commercial and non-commercial use with attribution.

Author

Toshikatsu Oga — The HORIZ音s Co., Ltd. (Japan) 30 years in residential construction (carpenter → site supervisor → CM → AI engineer)